The invention relates to a target tracking device for target tracking missiles comprising an electro-optical seeker assembly mounted in a missile structure through gimbals, said seeker assembly responding to target radiation and providing target deviation signals, and actuator means for causing said seeker assembly to track a target, said actuator means being controlled by target deviation signals.
Target tracking missiles contain a seeker with a seeker assembly, which receives radiation from a target and is caused to point towards the target. The seeker assembly comprises an imaging optical system. The imaging optical system generates an image of an object scene in an image plane. Detector means generate target deviation signals. Actuator means are controlled by these target deviation signals. The actuator means keep the seeker assembly aligned with or pointing to the target. In addition, steering commands are generated, which steer the missile to the target.
The seeker assembly has to be stabilized and de-coupled from the movements of the missile. In prior art target tracking missiles, the imaging optical system is carried by a gimbal mounted gyro rotor. This gyro rotor is stabilized in space and de-coupled from the missile movements. The imaging optical system comprises a concave mirror, the optical axis of which forms a small angle with the axis of rotation of the gyro rotor. Thereby, the image of the object scene makes a gyrating movement in the image plane. A reticle or modulating disc is located in the image plane. A photoelectric detector is arranged behind the reticle. A. C. signals are derived from the signals of the photoelectric detector. The amplitude of these A. C. signals depends on, the amount of the target deviation, and the phase of these A. C. signals depends on the direction of the target deviation. These signals are applied to precession coils, which surround the gyro rotor. The gyro rotor is radially magnetized. Thereby, cyclic precession torques are exerted on the gyro rotor. These precession torques cause precession of the axis of rotation of the gyro rotor towards a detected target. In prior art missiles, these A. C. signals, at the same time, serve to generate steering signals for the missile.
In these prior art devices, the “angle of squint”, i.e. the angle between the axis of rotation of the gyro rotor and the longitudinal axis of the missile is limited.
Picture processing seeker assemblies are known. In such picture processing seeker assembies, a two-dimensional array of detector elements is provided in the image plane of the imaging optical system, similar to a video camera. The detector elements respond to infrared radiation. A target is recognized and a target deviation is determined by picture processing.
For highly maneuverable missiles, target tracking devices or seeker heads are required which permit large angles of squint. The space required by the device and the the weight of the device should be low.